Contactless Card

ABSTRACT

The present invention aims at providing a contactless card that enables a reader/writer to identify which card such reader/writer is communicating with in a set of card identification processes and that improves the possibility of protecting the cardholder&#39;s privacy. Contactless card ( 200 ) includes: power detection unit ( 203 ); random number ID generation unit ( 210 ) that determines an identifier that identifies card ( 200 ), every time power detection unit ( 203 ) detects that electric power has been supplied; ID storage unit ( 2081 ) that holds the determined identifier; sending/receiving circuit ( 204 ) that receives a command requesting that the identifier that identifies card ( 200 ) should be sent to reader/writer ( 100 ), and sending/receiving circuit ( 204 ) sends, to reader/writer ( 100 ), the determined identifier in the case where the received command is a first-received command, and the held identifier in the case where the received command is a second- or later-received command.

TECHNICAL FIELD

The present invention relates to a contactless card that communicateswith a reader/writer wirelessly.

BACKGROUND ART

Conventionally, the timeslot method has been used for a communicationbetween a contactless card that sends/receives data and a reader/writerthat identifies the contactless card, using the electromagneticinduction method or the like. In the case where plural contactless cardssimultaneously exist within a communication area covered by areader/writer and such plurality of contactless cards simultaneouslysend response signals in response to polling performed by thereader/writer, any of the contactless cards cannot normally communicatewith the reader/writer due to the collision of response signals. Thetimeslot method prevents the occurrence of such situations.

The following describes how a communication is carried out in accordancewith the timeslot method.

(1) The reader/writer sends a request command in order to detect thepresence of a contactless card. The request command includes “slotnumber” which is the number of time periods (timeslots) in which thecontactless card can make an initial response.

(2) After receiving the request command, the contactless card returns aninitial response that includes its card ID in one of the timeslots. Thecontactless card determines, on its own, a timeslot in which it makes aninitial response.

(3) When detecting a collision of initial responses, the reader/writersends a request command again. As a result, the counting of thetimeslots restarts.

(4) The reader/writer can identify all contactless cards when nocollision of initial responses is detected in any of the timeslots. Thismarks the completion of the card identification processing.

As a contactless card identification method employed by a reader/writer,there also exists the slot maker method in which a reader/writernotifies a contactless card of timing at which the contactless card canmake an initial response. Also in this method, the contactless carddetermines, on its own, a timeslot in which it makes an initialresponse.

In order that a reader/writer identifies each contactless card, acontactless card is required to use a card ID by which it is possible todistinguish such contactless card from another contactless card. Throughthe use of a card ID, the reader/writer identifies a contactless cardsuch reader/writer is communicating with. The above methods arestandardized as ISO/IEC14443-3 (Type B, initialization and anticollisionscheme).

DISCLOSURE OF INVENTION

However, conventional contactless cards include a Read Only Memory (ROM)that stores a specific value, and such value is used as a card ID. Thus,it is possible for a third party to estimate that the card ID that isused when the contactless card makes an initial response is anidentifier to identify a person who holds the contactless card(hereinafter referred to as a “cardholder”). This could lead to aviolation of the cardholder's privacy.

A contactless card returns an initial response that includes its card IDin response to a request command sent from a reader/writer. Therefore,it is possible to identify the range and time of the cardholder'sactivities by recording initial responses using plural readers/writersinstalled at different places and then by analyzing the recorded initialresponses. Thus, when same card ID is constantly used, it is impossiblethat the activities of the cardholder of the contactless card using suchcard ID are identified and his/her privacy is violated.

In order to address the above problem, it is conceivable that acontactless card that has received a request command sent from areader/writer makes an initial response, using a card ID that thereader/writer changes for each request command it receives. However,when a card ID is changed for each request command, it becomesimpossible for the reader/writer to communicate with a contactless cardthat uses a specific card ID. A contactless card is required to use thesame card ID through a set of card identification processes. “A set ofcard identification processes” refers to processes to be performed fromwhen a reader/writer sends a request command to a contactless card forthe first time until when the reader/writer identifies such contactlesscard.

The present invention has been conceived in view of the above problem,and it is an object of the present invention to provide a contactlesscard that enables a reader/writer to identify which contactless cardsuch reader/writer is communicating with in a set of card identificationprocesses and that improves the possibility of protecting thecardholder's privacy.

In order to achieve the above problem, a contactless card of the presentinvention is a contactless card that communicates with a reader/writerafter being supplied with electric power, including: a power detectionunit that detects electric power enough to communicate with thereader/writer; an identifier determination unit that determines anidentifier that identifies the contactless card, every time the powerdetection unit detects the enough electric power; a determinedidentifier storage unit that holds the identifier determined by theidentifier determination unit; a receiving unit that receives, from thereader/writer, a command requesting that the identifier that identifiesthe contactless card should be sent to the reader/writer; and a sendingunit that sends, to the reader/writer, (i) the identifier determined bythe identifier determination unit in the case where the command receivedby the receiving unit is a first-received command, and (ii) theidentifier held in the determined identifier storage unit in the casewhere the command received by the receiving unit is a second- orlater-received command. Here, “detects electric power enough tocommunicate with the reader/writer” means to detect that electric powerhas been supplied. Furthermore, “the power detection unit detects theenough electric power” means that the power detection unit detects thatelectric power has been supplied.

The identifier determination unit determines an identifier thatidentifies the contactless card every time the power detection unitdetects the enough electric power. Accordingly, it is possible toincrease the possibility that an identifier that is difficult for athird party to guess is determined every time the power detection unitdetects the enough electric power. Therefore, it is difficult for athird party to identify the activities of the cardholder even whenidentifiers used by the contactless card of the present invention arerecorded and analyzed. In other words, the contactless card according tothe present invention improves the possibility of protecting thecardholder's privacy.

Furthermore, the sending unit sends the determined identifier or theidentifier held in the determined identifier storage unit that is thesame as the determined identifier. Accordingly, it becomes possible forthe reader/writer to perform a communication, recognizing that suchreader/writer is communicating with the contactless card of the presentinvention.

The identifier determination unit may generate an identifier every timethe power detection unit detects the enough electric power, and maydetermine the generated identifier as the identifier that identifies thecontactless card.

The identifier determination unit may generate the identifier made up ofa fixed value portion and a random number portion. Accordingly, itbecomes possible for the fixed value portion in the identifier of thecontactless card according to the present invention to include the cardissuer's ID, the service type, or the like. The object of the presentinvention is achievable by the random number portion. Therefore, it ispossible for the reader/writer to obtain the card information bychecking the fixed value portion in the identifier. Furthermore, itbecomes possible to prevent the activities of the cardholder from beingidentified.

The contactless card of the present invention may further include acandidate identifier storage unit that holds candidate identifiers,wherein the identifier determination unit may select one of thecandidate identifiers held in the candidate identifier storage unitevery time the power detection unit detects the enough electric power,and may determine the selected candidate identifier as the identifierthat identifies the contactless card.

The identifier determination unit determines the identifier using arandom number. With this structure in which an identifier is determinedusing a random number, it becomes impossible for a third party to guessthe determined identifier. Furthermore, it becomes impossible for athird party to guess a next identifier to be generated.

The contactless card of the present invention may further include acommunication end detection unit that detects an end of a communicationbetween the reader/writer and the receiving unit and the sending unit,wherein the identifier determination unit may determine a new identifierand the determined identifier storage unit may hold the new identifierin the case where the communication end detection unit detects the endof the communication.

After the end of a communication carried out with the contactless card,the reader/writer can regard such contactless card as a different cardin a later communication. This allows the contactless card to change theidentifier thereof. Accordingly, it becomes possible to further improvethe possibility of preventing the privacy of the cardholder of thecontactless card from being violated.

The communication between the reader/writer and the contactless card isin compliance with ISO/IEC14443, and the identifier sent by the sendingunit is set as a Pseudo-Unique Proximity Integrated Circuit Card (PICC)identifier included in a response to a request command that is sent fromthe reader/writer to the contactless card.

A contactless card of the present invention may further include: a modejudgment unit that judges an operation mode in which the contactlesscard operates; a random identifier generation unit that generates anidentifier in a random manner; and a specific identifier generation unitthat generates a specific identifier, wherein the identifierdetermination unit may determine one of the following identifiers as theidentifier that identifies the contactless card based on the judgmentmade by the mode judgment unit: the identifier generated by the randomidentifier generation unit; and the identifier generated by the specificidentifier generation unit.

The contactless card according to the present invention determines anidentifier depending on the operation mode. Accordingly, in the casewhere the cardholder does not care about his/her privacy, the use of aspecific identifier (fixed identifier or the like) enables suchcardholder to receive a special service. In contrast, when thecardholder cares about his/her privacy, the use of a randomly generatedidentifier results in improved convenience of the cardholder.

The operation mode may include: an inspection mode indicating that thecontactless card is in an inspection process; and a use mode indicatingthat the contactless card is in use by a public user, and the identifierdetermination may (i) determine, in the inspection mode, that theidentifier generated by the specific identifier generation unit is theidentifier that identifies the contactless card, and (ii) determine, inthe use mode, that the identifier generated by the random identifiergeneration unit is the identifier that identifies the contactless card.

The use of the contactless card according to the present inventionallows an inspection machine to use a specific identifier in aninspection process when such inspection machine is in an environmentwhere it is possible to perform a test through a contactlesscommunication. It is possible for the inspection machine to hold, as apattern, an identifier included in a response from the contactless card.Accordingly, it becomes not necessary to perform a calculation relatedto a card ID, as a result of which the efficiency of inspection isincreased. Meanwhile, since a randomly generated identifier is used whenthe contactless card is in use, it becomes possible to protect thecardholder's privacy.

What is more, the use of the contactless card according to the presentinvention allows the inspection machine to hold in advance testpatterns.

The specific identifier generation unit may generate the identifierbased on information stored in a read only memory where informationstored therein is not rewritable.

The specific identifier generation unit may generate the identifierbased on information stored in a non-volatile memory where informationstored therein is rewritable. The non-volatile memory is one of anelectrically erasable programmable read only memory, a ferroelectricrandom access memory, a magnetoresistive random access memory, and anovonic unified memory.

As described above, it is possible for the present invention to providea contactless card that enables a reader/writer to identify whichcontactless card such reader/writer is communicating with in a set ofcard identification processes and that improves the possibility ofprotecting the cardholder's privacy.

Furthermore, it is also possible to embody the present invention as thefollowing: a method that includes, as its steps, the characteristicunits included in the contactless card of the present invention; aprogram that causes a computer to execute such steps; a storage mediumsuch as a CD-ROM in which such program is stored; and an integratedcircuit. It should be also noted that such program can be distributedover a transmission medium such as a communication network.

The disclosure of Japanese Patent Application No. 2004-118807 filed onApr. 14, 2004 including specification, drawings and claims isincorporated herein by reference in its entirety.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the invention. In the Drawings:

FIG. 1 is a diagram illustrating a situation in which an embodiment iscarried out;

FIG. 2 is a diagram showing a structure of a request command;

FIG. 3 is a diagram showing a structure of an initial response;

FIG. 4 is a diagram showing a set of card identification processes;

FIG. 5 is a diagram showing a set of card identification processes andcommunications of actual data;

FIG. 6 is a module structure diagram showing structures of areader/writer and a contactless card according to a first embodiment;

FIG. 7 is a block diagram showing a function of the reader/writer andthe contactless card according to the first embodiment;

FIG. 8 is a flowchart showing steps performed by the contactless cardaccording to the first embodiment when making an initial response thatincludes a card ID;

FIG. 9 is a diagram illustrating an effect produced by the firstembodiment;

FIG. 10 is a block diagram showing a function of the contactless cardaccording to the first embodiment;

FIG. 11 is a diagram showing a contactless card according to a secondembodiment in the manufacturing process;

FIG. 12 is a module structure diagram showing the contactless cardaccording to the second embodiment;

FIG. 13 is a block diagram showing a function of the contactless cardaccording to the second embodiment;

FIG. 14 is a flowchart showing steps performed by the contactless cardaccording to the second embodiment when making an initial response thatincludes a card ID;

FIG. 15 is a block diagram showing a function of the contactless cardaccording to the second embodiment;

FIG. 16 is a block diagram showing a function of the contactless cardaccording to the second embodiment;

FIG. 17 is a flowchart showing steps performed by the contactless cardaccording to the second embodiment when making an initial response thatincludes a card ID;

FIG. 18 is a module structure diagram showing a contactless cardaccording to a third embodiment;

FIG. 19 is a block diagram showing a function of the contactless cardaccording to the third embodiment;

FIG. 20 is a diagram showing a structure of a card ID according to afourth embodiment;

FIG. 21 is an external view showing a mobile terminal device and acontactless card according to a fifth embodiment;

FIG. 22 is a block diagram showing functions of the mobile terminaldevice and the contactless card according to the fifth embodiment;

FIG. 23 is a diagram showing a part of the function of the contactlesscard according to the first embodiment being implemented as an LSI;

FIG. 24 is a diagram showing a part of the function of the contactlesscard according to the second embodiment being implemented as an LSI; and

FIG. 25 is a diagram showing a part of the function of the contactlesscard according to the third embodiment being implemented as an LSI;

BEST MODE FOR CARRYING OUT THE INVENTION

The following describes the best mode for carrying out the presentinvention with reference to the drawings.

A description is given of an embodiment of a contactless card thatcommunicates with a reader/writer in compliance with ISO/IEC14443-3(Type B, initialization and anticollision scheme). ISO/IEC14443-3 (TypeB, initialization and anticollision scheme) is one of the protocolsemployed, for example, for ticket gates in public transportationfacilities and the like. Referring to FIG. 1, suppose the case wherecontactless card 200 and contactless card 300 functioning as traintickets simultaneously approach reader/writer 100 functioning as aticket gate.

According to ISO/IEC14443-3 (Type B, initialization and anticollisionscheme), contactless cards are identified by the following procedures.

First, reader/writer 100, being a ticket gate, sends a request command.The request command is a signal in the format shown in FIG. 2. Thenumber of timeslots (N) is identified in three bits in “PARM”, includedin the request command, starting from “bit1 (“b1” in FIG. 2)” to “bit3(“b3” in FIG. 2)”. The identified number of timeslots (N) is notified tocontactless card 200 and contactless card 300. Each of contactless card200 and contactless card 300 makes an initial response in one of thetimeslots 1 to N.

The following assumes that the number of timeslots (N) is “4”. In otherwords, in response to the request command, each of contactless card 200and contactless card 300 selects one timeslot from among timeslots 1 to4, and makes an initial response in the selected timeslot.

An initial response is a signal in the format shown in FIG. 3. Theinitial response includes: card ID (PUPI) that identifies thecontactless card; APP Data for notifying reader/writer 100 ofinformation about an application included in the contactless card; andProtocol Inf for notifying reader/writer 100 of information about aprotocol that is used for carrying out a communication withreader/writer 100. Contactless card 200 and contactless card 300 make aninitial response to reader/writer 100 after setting a card ID (PUPI),APP Data and Protocol Inf.

Upon receipt of the initial responses from contactless card 200 andcontactless card 300, reader/writer 100 judges whether or not there is acollision of the initial responses with reference to the CRC value orthe like of the received initial responses.

Referring to FIG. 4, in the first card identification process,reader/writer 100 sends request command R1. In response to such requestcommand RI, contactless card 200 and contactless card 300 make theirrespective initial responses in timeslot 2. In other words, it is in thesame timing, timeslot 2, that contactless card 200 makes initialresponse A21 and contactless card 300 makes an initial response A31.Thus, reader/writer 100 detects that there is a collision of the initialresponses. Accordingly, a card identification process is to be performedagain.

In the second card identification process, reader/writer 100 sendsrequest command R2. In response to such request command R2, contactlesscard 200 makes initial response A22 in timeslot 3, whereas contactlesscard 300 makes initial response A32 in timeslot 2. In other words,contactless card 200 and contactless card 300 make their respectiveinitial responses in different timeslots. In this case, reader/writer100 detects no occurrence of collision of initial responses. In otherwords, it is possible for reader/writer 100 to identify contactless card200 and contactless card 300. Accordingly, the card identificationprocess completes.

In this specification, “a set of card identification processes” refersto processes to be performed from when the reader/writer sends a requestcommand to a contactless card for the first time until when thereader/writer identifies such contactless card. Thus, in an exampleillustrated in FIG. 4, the first card identification process and thesecond card identification process make up “a set of card identificationprocesses”.

At the completion of “a set of card identification processes”,contactless card 200 and contactless card 300 communicate actual databetween them via reader/writer 100. FIG. 5 is a diagram showing “a setof card identification processes” and communications of actual data.

When contactless card 200 and contactless card 300 simultaneously existwithin a predetermined range of area from reader/writer 100 and power issupplied to contactless card 200 and contactless card 300 (illustratedas “Power On” in FIG. 5), a set of card identification processes at thestart of communication is performed.

At the completion of a set of card identification processes at the startof communication, contactless card 200 and contactless card 300communicate actual data between them via reader/writer 100.

After the actual data is communicated, a set of processes at the end ofcommunication is performed. In such set of processes, reader/writer 100sends, to each of the cards, Deselect command that indicates the end ofthe communication.

Meanwhile, it is also possible to assume the following case as anexample, as shown in FIG. 1, where contactless card 200 and contactlesscard 300 simultaneously approach reader/writer 100: contactless card 200is a master card that stores the name of the cardholder of contactlesscard 200, and contactless card 300 approaches reader/writer 100simultaneously with contactless card 200 with the intention ofduplicating the cardholder's name into a memory of contactless card 300.For simplification purposes, the following only describes “a set of cardidentification processes” to be performed from when reader/writer 100sends a request command for the first time until when reader/writer 100identifies contactless card 200.

First Embodiment

FIG. 6 is a diagram showing structures of reader/writer 100 andcontactless card 200.

Reader/writer 100 is made up of antenna 101, sending/receiving circuit102, central processing unit (CPU) 103, and memory 104. Memory 104stores a program to be executed by CPU 103 and is used as a storage unitfor storing data to be processed at program execution time. Memory 104may be implemented as, for example, a non-volatile memory that allowsthe rewriting of information, or may be implemented as a combination ofa ROM that does not allow the rewriting of information and that stores aprogram and data, and a RAM that is used as a temporary work area atprogram execution time.

Contactless card 200 is made up of antenna 201, power storage unit 202,power detection unit 203, sending/receiving circuit 204, centralprocessing unit (CPU) 205, RAM 208, and ROM 207. Power storage unit 202stores power, using an induced electromotive force, when contactlesscard 200 exists within a predetermined range of area from reader/writer100. Power detection unit 203 detects power that is enough forsending/receiving circuit 204 to communicate with reader/writer 100. Inother words, power detection unit 203 detects that power has beensupplied. In further other words, power detection unit 203 detects thatpower storage unit 202 has stored power.

ROM 207 stores a program for processing a command from reader/writer 100and is used as a storage unit that stores data to be processed atprogram execution time. The data to be processed includes data to bestored. RAM 208 may be implemented as, for example, a non-volatilememory that allows the rewriting of information.

ROM 207 stores random number ID generation program 210A for generating acard ID using a random number. RAM 208 stores a card ID that isgenerated by CPU 205 executing random number ID generation program 210A.RAM 208 further stores a first request judgment flag that indicateswhether or not a request command received by sending/receiving circuit204 in “a set of card identification processes” is the first requestcommand.

Furthermore, ROM 207 stores first request judgment program 211A forjudging whether or not a request command received by sending/receivingcircuit 204 in “a set of card identification processes” is the firstrequest command. ROM 207 further stores extraction program 212A forextracting the card ID stored in RAM 208.

Random number ID generation program 210A, first request judgment program211A, and extraction program 212A stored in ROM 207 are executed by CPU205.

FIG. 7 is a functional diagram showing an internal structure ofcontactless card 200 shown in FIG. 6. The following description isprovided with reference to FIG. 7. The function of random number IDgeneration unit 210 is implemented by CPU 205 executing random number IDgeneration program 210A. The function of first request judgment unit 211is implemented by CPU 205 executing first request judgment program 211A.The function of extraction unit 212 is implemented by CPU 205 executingextraction program 212A.

One or more, or all of random number ID generation unit 210, firstrequest judgment unit 211, and extraction unit 212 may be implemented assoftware or as dedicated hardware.

Random number ID generation unit 210 is an example of the identifierdetermination unit of the contactless card according to the presentinvention.

ID storage unit 2081 is an area in RAM 208 in which the card ID isstored. First request judgment flag storage unit 2082 is an area in RAM208 in which the first request judgment flag is stored.

The first request judgment flag is set to the default value, e.g., “0”,until power storage unit 202 stores power. The first request judgmentflag is set to, e.g., “1” that is different from the default value, whensending/receiving circuit 204 first receives a request command in “a setof card identification processes” after power storage unit 202 storespower. When sending/receiving circuit 204 receives a request command inthe case where the first request judgment flag is set to, e.g., “1” thatis different from the default value, it means that such request commandis the second or a later request command in “a set of cardidentification processes”.

First request judgment unit 211 changes the value of the first requestjudgment flag.

FIG. 8 is a flowchart showing the steps performed by contactless card200 when making an initial response that includes a card ID.

Here, suppose the case where power detection unit 203 detects that powerstorage unit 202 has stored power.

When sending/receiving circuit 204 receives a request command fromreader/writer 100 (S201), first request judgment unit 211 extracts thefirst request judgment flag stored in first request judgment flagstorage unit 2082 (S202). First request judgment unit 211 judges whetheror not the request command received by sending/receiving circuit 204 isthe first request command, based on the value of the extracted firstrequest judgment flag (S203). When the value of the first requestJudgment flag is the default value, e.g., “0”, first request judgmentunit 211 judges that the received request command is the first requestcommand. Meanwhile, when the value of the first request judgment flag isdifferent from the default value, e.g., “1”, first request judgment unit211 judges that the received request command is not the first requestcommand. In other words, first request judgment unit 211 judges that thereceived request command is the second or a later request command.

When first request judgment unit 211 judges that the received requestcommand is the first request command (Yes in S203), random number IDgeneration unit 210 generates a card ID using a random number (S204).Since a card ID is generated using a random number, it is difficult fora third party to guess the card ID. Furthermore, it is difficult for athird party to guess a next card ID to be generated. Random number IDgeneration unit 210 may generate a card ID through a calculation thatuses a random number or may generate a card ID using a predeterminedrandom number sequence. In other words, random number ID generation unit210 generates a card ID using a random number so that a third partycannot guess the card ID. Random number ID generation unit 210 storesthe generated card ID into ID storage unit 2081 (S205).

First request judgment unit 211 changes the value, being the defaultvalue, of the first request judgment flag stored in first requestjudgment flag storage unit 2802 into a value, e.g., “1”, that isdifferent from the default value (S206). Such change is made so that thesame card ID is used in a set of card identification processes.

Extraction unit 212 extracts the card ID stored in ID storage unit 2081(S207). Sending/receiving circuit 204 sends, to reader/writer 100, aninitial response that includes the extracted card ID (S208).

Meanwhile, when first request judgment unit 211 judges that the requestcommand received by sending/receiving circuit 204 is not the firstrequest command (No in S203), extraction unit 212 extracts the card IDstored in ID storage unit 2081 (S207). Sending/receiving circuit 204sends, to reader/writer 100, an initial response that includes theextracted card ID (S208).

In other words, also in the case where the request command received bysending/receiving circuit 204 is the second or a later request command,sending/receiving circuit 204 sends, to reader/writer 100, the card IDthat is the same as the card ID to be sent in the case where thereceived request command is the first request command.

As described above, in the first embodiment, contactless card 200 sendsan initial response that includes the same card ID to reader/writer 100.In a set of card identification processes, regardless of whether thereceived request command is the first request command or the second or alater request command. Accordingly, it becomes possible forreader/writer 100 to communicate with contactless card 200, recognizingthat reader/writer 100 is communicating with contactless card 200.

Furthermore, since contactless card 200 generates a card ID using arandom number every time power is supplied to contactless card 200, itis difficult for a third party to guess the card ID generated bycontactless card 200. FIG. 9 is a diagram showing that (1) contactlesscard 200 makes initial responses by using a different card ID that isnewly generated every time power is supplied and that (2) contactlesscard 200 sends, to reader/writer 100, initial responses in a set of cardidentification processes, the initial responses including the same cardID through such set of card identification processes.

As shown in FIG. 9, every time power is supplied and the first requestcommand is received, contactless card 200 makes an initial responseusing a card ID that is difficult for a third party to guess. As aresult, there is a lower possibility of being able to identify the rangeand time of activities of the cardholder of contactless card 200 evenwhen initial responses are recorded in reader/writer 100 and suchrecords are analyzed. Accordingly, it becomes possible to protect theprivacy of the cardholder of contactless card 200.

Furthermore, as shown in FIG. 10, contactless card 200 may be replacedby contactless card 200A that includes, instead of random number IDgeneration unit 210, candidate ID storage unit 230 that stores pluralcandidate card IDs and ID selection unit 231. When first requestJudgment unit 211 judges that the received request command is the firstrequest command, ID selection unit 231 selects and extracts one of theplural candidate card IDs stored in candidate ID storage unit 230, andstores the extracted candidate card ID into ID storage unit 2081. Inthis case, it is possible to protect the privacy of the cardholder ofcontactless card 200 as in the case where random number ID generationunit 210 generates a card ID using a random number, provided that theconfidentiality of the plural candidate card IDs is sufficientlyensured.

Second Embodiment

FIG. 11 is a diagram showing contactless card 200B according to thesecond embodiment in the manufacturing process. Contactless card 200B isintegrated with inspection unit 251 when in the manufacturing process,and is separated from inspection unit 251 immediately before contactlesscard 200B is completed as a product. In cases such as where a memory ofeach of plural contactless cards 200B needs to be initialized in acollective manner in the inspection process in the manufacturing,reader/writer 100 is sometimes required to communicate with such pluralcontactless cards 200B simultaneously. In this case, all of suchcontactless cards 200B are required to make an initial response thatincludes a predetermined card ID (hereinafter referred to as “fixed cardID”). Meanwhile, it is not allowed for contactless card 200B completedas a product to make an initial response that includes the fixed card IDfor the reason that reader/writer 100 needs to judge which contactlesscard reader/writer 100 is communicating with and that the cardholder'sprivacy needs to be protected.

Thus, it is necessary for contactless card 200B to judge whether togenerate a fixed card ID or a non-fixed card ID.

In order to do so, contactless card 200B according to the secondembodiment has a function of judging whether to generate a fixed card IDor a non-fixed card ID, in addition to the functions of contactless card200 described in the first embodiment. The following description focuseson such difference between contactless card 200B and contactless card200. Note that as shown in FIG. 11, contactless card 200B has voltagemeasurement unit 250. In the second embodiment, since contactless card200B and inspection unit 251 are integrated to each other whencontactless card 200B is in the manufacturing process, there is wiringconnecting contactless card 200B and inspection unit 251, and voltagemeasurement unit 250 obtains a voltage value of 0V in this case.Meanwhile, when contactless card 200B is in use as a product,contactless card 200B and inspection unit 251 are separated from eachother. Thus, wiring connecting contactless card 200B and inspection unit251 is broken, and voltage measurement unit 250 obtains a voltage valueof V₀ (e.g., 5V).

FIG. 12 is a diagram showing a structure of contactless card 200Baccording to the second embodiment. Contactless card 200B is made up ofantenna 201, power storage unit 202, power detection unit 203,sending/receiving circuit 204, CPU 205, ROM 207A, and RAM 208B, as inthe case of contactless card 200 of the first embodiment, and furtherincludes voltage measurement unit 250.

ROM 207A stores random number ID generation program 210A, first requestjudgment program 211A, and extraction program 212A. ROM 207A furtherstores fixed ID generation program 213A and mode judgment program 214A.Each of the programs stored in ROM 207A is executed by CPU 205.

Fixed ID generation program 213A is a program for generating a fixedcard ID.

Mode judgment program 214A is a program for judging an operation mode.Here, suppose that there are “inspection mode” and “use mode” asoperation modes. “Inspection mode” indicates that contactless card 200Bis in the manufacturing process and that the generation of a fixed cardID is required for inspection purposes. “Use mode” indicates thatcontactless card 200B is in use as a product and that the generation ofa card ID using a random number is required for the purpose ofidentifying a contactless card being communicated with and for thepurpose of protecting the cardholder's privacy. One of “inspection mode”and “use mode” is selected based on a voltage value measured by voltagemeasurement unit 250.

RAM 208A stores a card ID that is generated by CPU 205 by executingrandom number ID generation program 210A or fixed ID generation program213A. RAM 208A further stores a first request judgment flag and a modejudgment flag that indicates whether a card ID should be generated in“inspection mode” or in “use mode”.

FIG. 13 is a functional diagram showing an internal structure ofcontactless card 200B shown in FIG. 12. The following description isprovided with reference to FIG. 13. The function of fixed ID generationunit 213 is implemented by CPU 205 executing fixed ID generation program213A. The function of mode judgment unit 214 is implemented by CPU 205executing mode judgment program 214A.

One or both of fixed ID generation unit 213 and mode judgment unit 214may be implemented as software or as dedicated hardware.

Random number ID generation unit 210 and fixed ID generation unit 213are an example of the identifier determination units of the contactlesscard according to the present invention. Furthermore, random number IDgeneration unit 210 is also an example of the random identifiergeneration unit of the contactless card according to the presentinvention, and fixed ID generation unit 213 is also an example of thespecific identifier generation unit of the contactless card according tothe present invention.

Fixed ID generation unit 213 generates a fixed card ID based on, forexample, information stored in ROM 207A. In the case where contactlesscard 200B has a ROM or a non-volatile memory other than ROM 207A, fixedID generation unit 213 may generate a fixed card ID based on informationstored in such ROM or non-volatile memory other than ROM 207A. Anexample of the information is an identifier that is assigned tocontactless card 200B at the time of manufacturing to identifycontactless card 200B. The non-volatile memory is an ElectricallyErasable Programmable Read Only Memory (EEPROM), a Ferroelectric RandomAccess Memory (FeRAM), a Magnetoresistive Random Access Memory (MRAM),an Ovonic Unified memory (OUM), or the like.

Mode judgment flag storage unit 2083 is an area in RAM 208A in which themode judgment flag is stored.

The mode judgment flag is set to the default value, e.g., “0”, whencontactless card 200B is in the manufacturing process. Meanwhile, whencontactless card 200B is in use as a product, the mode judgment flag isset to a value different from the default value, e.g., “1”.

Mode judgment unit 214 changes the value of the mode judgment flag basedon the voltage value measured by voltage measurement unit 250.

FIG. 14 is a flowchart showing the steps performed by contactless card200B when making an initial response that includes a card ID.

Here, suppose the case where power detection unit 203 detects that powerstorage unit 202 has stored power.

When sending/receiving circuit 204 receives a request command fromreader/writer 100 (S301), first request judgment unit 211 extracts thefirst request judgment flag stored in first request judgment flagstorage unit 2082 (S302). First request judgment unit 211 judges whetheror not the request command received by sending/receiving circuit 204 isthe first request command, based on the value of the extracted firstrequest judgment flag (S303).

When first request judgment unit 211 judges that the received requestcommand is the first request command (Yes in S303), mode judgment unit214 extracts the mode judgment flag stored in mode judgment flag storageunit 2083 (S304). Mode judgment unit 214 judges whether to generate acard ID in “inspection mode” or in “use mode”, based on the value of theextracted mode judgment flag (S305).

Mode judgment unit 214 judges that a card ID should be generated in“inspection mode” when the value of the mode judgment flag is thedefault value, e.g., “0” (“inspection mode” in S305). Meanwhile, modejudgment unit 214 judges that a card ID should be generated in “usemode” when the value of the mode judgment flag is different from thedefault value, e.g., “1” (“Use mode” in S305).

When mode judgment unit 214 judges that a card ID should be generated in“inspection mode” (“inspection mode” in S305), fixed ID generation unit213 generates a fixed card ID that is previously determined (S306), andthen stores the generated card ID into ID storage unit 2081 (S308).Meanwhile, when mode judgment unit 214 judges that a card ID should begenerated in “use mode” (“Use mode” in S305), random number IDgeneration unit 210 generates a card ID, using a random number (S307),and then stores the generated card ID into ID storage unit 2081 (S308).

First request judgment unit 211 changes the value, being the defaultvalue, of the first request judgment flag stored in first requestjudgment flag storage unit 2802 into a value that is different from thedefault value, e.g., “1” (S309).

Extraction unit 212 extracts the card ID stored in ID storage unit 2081(S310). Sending/receiving circuit 204 sends, to reader/writer 100, aninitial response that includes the extracted card ID (S311).

Meanwhile, when first request judgment unit 211 judges that the requestcommand received by sending/receiving circuit 204 is not the firstrequest command (No in S303), extraction unit 212 extracts the card IDstored in ID storage unit 2081 (S310). Sending/receiving circuit 204sends, to reader/writer 100, an initial response that includes theextracted card ID (5311).

In other words, also in the case where the request command received bysending/receiving circuit 204 is the second or a later request command,sending/receiving circuit 204 sends, to reader/writer 100, the card IDthat is the same as the card ID to be sent in the case where thereceived request command is the first request command.

As described above, in the second embodiment, contactless card 200Bjudges whether an operation mode is “inspection mode” or “use mode”, andgenerates a card ID based on such judgment. Accordingly, whencontactless cards 200B are in the manufacturing process, it becomespossible for reader/writer 100 to communicate with each of pluralcontactless card 200B in a collective manner, using a fixed card ID.Meanwhile, when contactless card 200B is in lo use, contactless card200B communicates with reader/writer 100, using a card ID that isdifficult for a third party to guess. This makes it possible to protectthe privacy of the cardholder of contactless card 200B.

In “inspection mode”, it is possible for an inspection machine tocommunicate with plural contactless card 200B, via reader/writer 100,using a fixed card ID, so as to inspect such plurality of contactlesscard 200B. By holding a fixed card ID, it becomes not necessary for theinspection machine to perform a calculation related to a card ID, as aresult of which the efficiency of inspection is increased.

Note that operation modes are not limited to “inspection mode” and “usemode”, which may therefore be a mode in which memory initialization ispossible and a mode in which memory initialization is not possible. Ineither case, contactless card 200B generates a card ID depending on theoperation mode.

For example, in the case where the cardholder does not care abouthis/her privacy, contactless card 200B generates a fixed card ID in amode for generating a fixed card ID. In this case, the use of a fixedcard ID allows the cardholder to receive a special service. In contrast,in the case where the cardholder cares about his/her privacy,contactless card 200B generates a card ID in a mode for generating acard ID using a random number. In this case, the use of such card IDresults in improved convenience of the cardholder.

A fixed card ID may be stored in a ROM that does not allow the rewritingof information. In this case, the above inspection machine or the likemay previously hold test patterns.

Furthermore, a fixed card ID may be stored in a non-volatile memory thatallows the rewriting of information. In this case, it is possible torewrite a fixed card ID. An example of the non-volatile memory is anEEPROM, a FeRAM, an MRAM, an OUM, or the like.

Note that fixed ID generation unit 213 may generate a card ID bysequentially using a card ID included in a known card ID sequence,rather than generating a fixed card ID. In this case, it is possible toachieve the same effect as is produced through the use of a fixed cardID, by allowing reader/writer 100 to know in advance a card ID to besent thereto from the above card ID sequence and from the card ID thatis used when the use of the card ID sequence starts.

Moreover, as shown in FIG. 15, contactless card 200B may be replaced bycontactless card 200C that further includes area detection unit 220.Area detection unit 220 detects that contactless card 200C exists in aspecific area. Area detection unit 220 changes the value of the modejudgment flag stored in mode judgment flag storage unit 2083 based onthe result of the detection.

For example, suppose the case where the cardholder of contactless card200C is an employee of a certain company. When such employee enters abuilding owned by the company with contactless card 200C on him/her,area detection unit 220 detects that contactless card 200C exists in thebuilding. In this case, area detection unit 220 changes the value of themode judgment flag into a value that indicates that a fixed card IDshould be generated. Meanwhile, when detecting that contactless card200C does not exist in the building, area detection unit 220 changes thevalue of the mode judgment flag into a value that indicates that a cardID should be generated using a random value.

Accordingly, it becomes possible to supervise the activities ofemployees when they are inside a company building, with their privaciesbeing protected when they are outside the company building.

Furthermore, as shown in FIG. 16, contactless card 200B may be replacedby contactless card 200BB that is a result of deleting first requestjudgment unit 211 and first request judgment flag storage unit 2082 fromcontactless card 200B. In this case, as shown in FIG. 17, the operationof contactless card 200BB is a result of deleting, from the steps shownin FIG. 14, the following steps performed by first request judgment unit211: a step of extracting the first request judgment flag (S302); a stepof judging whether or not a request command is the first request command(S303); and a step of changing the value of the first request judgmentflag (S309).

Contactless card 200BB is capable of producing the effect that isproduced by contactless card 200B by generating a card ID depending onthe operation mode.

Third Embodiment

FIG. 18 is a diagram showing a structure of contactless card. 200Daccording to the third embodiment.

Contactless card 200D is made up of antenna 201, power storage unit 202,power detection unit 203, sending/receiving circuit 204, CPU 205, ROM207B and RAM 208, as in the case of contactless card 200 of the firstembodiment.

ROM 207B stores random number ID generation program 210A, first requestjudgment program 211A, and extraction program 212A. ROM 207B furtherstores communication end judgment program 221A. Each of the programsstored in ROM 207B is executed by CPU 205.

Communication end judgment program 221A is a program for monitoringwhether or not a communication between sending/receiving circuit 204 andreader/writer 100 has ended.

FIG. 19 is a functional diagram showing an internal structure ofcontactless card 200D shown in FIG. 18. The following description isprovided with reference to FIG. 19. The function of communication endjudgment unit 221 is implemented by CPU 205 executing communication endjudgment program 221A.

Communication end judgment unit 221 may be implemented as software or asdedicated hardware.

The following describes an operation of communication end judgment unit221.

Communication end judgment unit 221 monitors whether or not acommunication between sending/receiving circuit 204 and reader/writer100 has ended. When judging that the communication betweensending/receiving circuit 204 and reader/writer 100 has ended,communication end judgment unit 221 changes the value of the firstrequest judgment flag stored in first request judgment flag storage unit2082 into the default value, e.g., “0”. When judging that thecommunication between sending/receiving circuit 204 and reader/writer100 has not ended yet, communication end judgment unit 221 does notchange the value of the first request judgment flag.

As is obvious from the descriptions of the first embodiment and secondembodiment, a card ID is newly generated when the value of the firstrequest judgment flag is the default value. Thus, contactless card 200Dnewly generates a card ID after judging that a communication betweensending/receiving circuit 204 and reader/writer 100 has ended andsubsequently receiving a request command.

After the end of a communication carried out with a contactless card,reader/writer 100 can regard such contactless card as a different cardin a later communication. This allows the contactless card to change thecard ID thereof. Accordingly, it becomes possible to protect the privacyof the cardholder of the contactless card.

Meanwhile, when communication end judgment unit 221 judges that thecommunication between sending/receiving circuit 204 and reader/writer100 has ended, random number ID generation unit 210 may generate a newcard ID, and store such new card ID into ID storage unit 2081. In thiscase, it is possible to lo perform in advance a step of generating a newcard ID that should be performed at the start of the next communication.

Fourth Embodiment

The aforementioned embodiments have described the case where a card IDis a random number or a fixed value. As shown in FIG. 20, a card ID maybe made up of portion 500 that contains a random number and portion 501that contains a fixed value. The object of the present invention isachievable when the same card ID is used through a set of cardidentification processes and when the same card ID is not constantlyused. Thus, a part of a card ID may be a fixed value.

The fixed value portion in the card ID of a contactless card can includethe card issuer's ID, the service type, and the like, with the object ofthe present invention achievable by the random number portion.Therefore, it is possible for the reader/writer to obtain the cardinformation by checking the fixed value portion in the card ID as wellas it becomes possible to prevent the activities of the cardholder frombeing identified.

In the above case, portion 500 containing a fixed value is generated byrandom number ID generation unit 210 and portion 501 containing a fixedvalue is generated by fixed ID generation unit 213.

Furthermore, the card ID may be stored into a non-volatile memory, inwhich case the fixed value portion of the card ID is rewritable.Accordingly, it becomes possible to further enhance the protection ofthe cardholder's privacy by the contactless card selecting a card IDdepending on the service and storing the value of the selected card IDinto the non-volatile memory.

Fifth Embodiment

As shown in FIG. 21, contactless card 200 may be replaced by contactlesscard 200E that is stored, when in use, in mobile terminal device 400such as a mobile phone. FIG. 22 is a diagram showing a structure ofmobile terminal device 400 and contactless card 200E.

Contactless card 200E does not have any antennas. When inserted intomobile terminal device 400, contactless card 200E communicates withreader/writer 100, utilizing antenna 401 equipped to mobile terminaldevice 400. Furthermore, contactless card 200E has power transmissionunit 260 instead of power storage unit 202. Power transmission unit 260transmits, to inside contactless card 200E, power supplied from powersupply unit 402 of mobile terminal device 400.

The following describes an operation of contactless card 200E. Afterpower detection unit 203 detects that power transmission unit 260 hastransmitted, to inside contactless card 200E, power supplied from powersupply unit 402, first request judgment unit 211 makes the followingjudgment: in the case where sending/receiving circuit 204 has received arequest command via antenna 401, first request judgment unit 211 judgeswhether such received request command is the first request command, orthe second or a later request command.

When the received request command is the first request command, randomnumber ID generation unit 210 generates a card ID using a random number,and sending/receiving circuit 204 sends, to reader/writer 100, aninitial response that includes the generated card ID via antenna 401.Furthermore, random number ID generation unit 210 stores the generatedcard ID into ID storage unit 2081.

Meanwhile, when the received request command is the second or a laterrequest command, sending/receiving circuit 204 sends, to reader/writer100, an initial response that includes the card ID stored in ID storageunit 2081 via antenna 401.

The fifth embodiment also produces the same effect as that of the firstembodiment, i.e., the effect of enabling reader/writer 100 tocommunicate with contactless card 200E in a set of card identificationprocesses, recognizing that reader/writer 100 is communicating withcontactless card 200E, and the effect of improving the possibility ofprotecting the privacy of the cardholder of contactless card 200E.

Supplement 1 to First to Fifth Embodiments

The functions of random number ID generation unit 210, ID storage unit2081, first request judgment unit 211, extraction unit 212,communication end judgment unit 221, mode judgment unit 214, and fixedID generation unit 213 that are described in the aforementionedembodiments are typically implemented by the CPU executing computerprograms. Such programs to be executed may be stored in a ROM includedin a contactless card or may be externally downloaded and stored into anon-volatile memory.

Supplement 2 to First to Fifth Embodiments

The above-described functions may be implemented as an LSI that is anintegrated circuit, by being combined with a program and hardwareresources such as a CPU, a RAM, a ROM, and a non-volatile memory. Suchfunctions may be incorporated into one chip on a function-by-functionbasis, or one or more or all of the functions may be incorporated intoone chip.

FIG. 23, FIG. 24, and FIG. 25 are diagrams showing example cases wherethe functions of the first embodiment, second embodiment, and thirdembodiment are respectively incorporated into integrated circuits. LSI1001, LSI 1002, and LSI 1003 are example integrated circuits. A portionenclosed by the doted lines in each of these diagrams denotes anintegrated circuit. The integrated circuits can be called “IC”, “systemLSI”, “super LSI”, and “ultra LSI” depending on the integration degree.

It should be noted that LSI is not the only example of the integratedcircuits, and thus they may be implemented as personal circuits orgeneral processors. It is also possible to utilize a Field ProgrammableGate Array (FPGA) that is programmable after manufacturing of LSI, or areconfigurable processor in which the connection and settings for thecircuit cell in the LSI can be reconfigurable.

Furthermore, along with the arrival of technique for incorporation intoan integrated circuit that replaces the LSI owing to a progress insemiconductor technology or another technique that has deviated from it,integration of the above-described functions may be carried out usingthe newly-arrived technology. Bio-technology may be cited as one of theexamples.

Also note that the aforementioned embodiments describe a contactlesscard that communicates with a reader/writer in compliance withISO/IEC14443-3 (Type B, initialization and anticollision scheme), butthe contactless card according the present invention may be acontactless card that performs a communication in compliance with Type Aof ISO/IEC14443-3 or with a standard called Type C.

INDUSTRIAL APPLICABILITY

The contactless card according to the present invention protects itscardholder's privacy through the use of a card ID that is difficult fora third party to guess. Furthermore, it is possible for a reader/writerto communicate with the contactless card of the present invention,recognizing that the reader/writer is communicating with suchcontactless card. Thus, the contactless card according to the presentinvention is also applicable for use in a system for performingcontactless communication (e.g., RF tag).

1. A contactless card that communicates with a reader/writer after beingsupplied with electric power, comprising: a power detection unitoperable to detect electric power enough to communicate with thereader/writer; an identifier determination unit operable to determine anidentifier that identifies the contactless card, every time the powerdetection unit detects the enough electric power; a determinedidentifier storage unit operable to hold the identifier determined bythe identifier determination unit; a receiving unit operable to receive,from the reader/writer, a command requesting that the identifier thatidentifies the contactless card should be sent to the reader/writer; anda sending unit operable to send, to the reader/writer, (i) theidentifier determined by the identifier determination unit in the casewhere the command received by the receiving unit is a first-receivedcommand, and (ii) the identifier held in the determined identifierstorage unit in the case where the command received by the receivingunit is a second- or later-received command.
 2. A contactless cardaccording to claim 1, wherein the identifier determination unit isoperable to generate an identifier every time the power detection unitdetects the enough electric power, and to determine the generatedidentifier as the identifier that identifies the contactless card.
 3. Acontactless card according to claim 2, wherein the identifierdetermination unit is operable to generate the identifier made up of afixed value portion and a random number portion.
 4. A contactless cardaccording to claim 1, further comprising a candidate identifier storageunit operable to hold candidate identifiers, wherein the identifierdetermination unit is operable to select one of the candidateidentifiers held in the candidate identifier storage unit every time thepower detection unit detects the enough electric power, and to determinethe selected candidate identifier as the identifier that identifies thecontactless card.
 5. A contactless card according to claim 1, whereinthe identifier determination unit is operable to determine theidentifier using a random number.
 6. A contactless card according toclaim 1, further comprising a communication end detection unit operableto detect an end of a communication between the reader/writer and thereceiving unit and the sending unit, wherein the identifierdetermination unit is operable to determine a new identifier and thedetermined identifier storage unit is operable to hold the newidentifier in the case where the communication end detection unitdetects the end of the communication.
 7. A contactless card according toclaim 1, wherein the communication between the reader/writer and thecontactless card is in compliance with ISO/IEC14443, and the identifiersent by the sending unit is set as a Pseudo-Unique Proximity IntegratedCircuit Card Identifier included in a response to a request command thatis sent from the reader/writer to the contactless card.
 8. A contactlesscard according to claim 1, further comprising: a mode judgment unitoperable to judge an operation mode in which the contactless cardoperates; a random identifier generation unit operable to generate anidentifier in a random manner; and a specific identifier generation unitoperable to generate a specific identifier, wherein the identifierdetermination unit is operable to determine one of the followingidentifiers as the identifier that identifies the contactless card basedon the judgment made by the mode judgment unit: the identifier generatedby the random identifier generation unit; and the identifier generatedby the specific identifier generation unit.
 9. A contactless cardaccording to claim 8, wherein the operation mode includes: an inspectionmode indicating that the contactless card is in an inspection process;and a use mode indicating that the contactless card is in use by apublic user, and the identifier determination unit is operable (i) todetermine, in the inspection mode, that the identifier generated by thespecific identifier generation unit is the identifier that identifiesthe contactless card, and (ii) to determine, in the use mode, that theidentifier generated by the random identifier generation unit is theidentifier that identifies the contactless card.
 10. A contactless cardaccording to claim 8, wherein the specific identifier generation unit isoperable to generate the identifier based on information stored in aread only memory where information stored therein is not rewritable. 11.A contactless card according to claim 8, wherein the specific identifiergeneration unit is operable to generate the identifier based oninformation stored in a non-volatile memory where information storedtherein is rewritable.
 12. A contactless card according to claim 11,wherein the non-volatile memory is one of an electrically erasableprogrammable read only memory, a ferroelectric random access memory, amagnetoresistive random access memory, and an ovonic unified memory. 13.A communication method performed by a contactless card to send anidentifier, the contactless card communicating with a reader/writerafter being supplied with electric power, the method comprising:detecting electric power enough to communicate with the reader/writer;determining an identifier that identifies the contactless card, everytime the enough electric power is detected in the detecting; storing thedetermined identifier into a storage unit; receiving, from thereader/writer, a command requesting that the identifier that identifiesthe contactless card should be sent to the reader/writer; and sending,to the reader/writer, (i) the determined identifier in the case wherethe received command is a first-received command, and (ii) theidentifier stored in the storage unit in the case where the receivedcommand is a second- or later-received command.
 14. An integratedcircuit in a contactless card that communicates with a reader/writerafter being supplied with electric power, the integrated circuitcomprising: a power detection unit operable to detect electric powerenough to communicate with the reader/writer; an identifierdetermination unit operable to determine an identifier that identifiesthe contactless card, every time the power detection unit detects theenough electric power; a determined identifier storage unit operable tohold the identifier determined by the identifier determination unit; areceiving unit operable to receive, from the reader/writer, a commandrequesting that the identifier that identifies the contactless cardshould be sent to the reader/writer; and a sending unit operable tosend, to the reader/writer, (i) the identifier determined by theidentifier determination unit in the case where the command received bythe receiving unit is a first-received command, and (ii) the identifierheld in the determined identifier storage unit in the case where thecommand received by the receiving unit is a second- or later-receivedcommand.
 15. A program for sending an identifier of a contactless cardthat communicates with a reader/writer after being supplied withelectric power, the program causing a computer to execute: detectingelectric power enough to communicate with the reader/writer; determiningan identifier that identifies the contactless card, every time theenough electric power is detected in the detecting; storing thedetermined identifier into a storage unit; receiving, from thereader/writer, a command requesting that the identifier that identifiesthe contactless card should be sent to the reader/writer; and sending,to the reader/writer, (i) the determined identifier in the case wherethe received command is a first-received command, and (ii) theidentifier stored in the storage unit in the case where the receivedcommand is a second- or later-received command.
 16. A storage medium inwhich a program for sending an identifier of a contactless card thatcommunicates with a reader/writer after being supplied with electricpower is stored, the program causing a computer to execute: detectingelectric power enough to communicate with the reader/writer; determiningan identifier that identifies the contactless card, every time theenough electric power is detected in the detecting; storing thedetermined identifier into a storage unit; receiving; from thereader/writer, a command requesting that the identifier that identifiesthe contactless card should be sent to the reader/writer; and sending,to the reader/writer, (i) the determined identifier in the case wherethe received command is a first-received command, and (ii) theidentifier stored in the storage unit in the case where the receivedcommand is a second- or later-received command.